<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <h3>小黑自动售货机</h3>
        <button @click="buy(5)">可乐5元</button>
        <button @click="buy(10)">咖啡10元</button>
        <div>{{balance}}</div>
    </div>
    <script src="../vue.js"></script>
    <script>
        const vue = new Vue({
        el:'#app',
        data:{
            balance:100
        },
        methods:{
            buy(price){
                this.balance-=price
            }
        }
        })
    </script>
</body>

</html>